1. Field of the Invention
The present invention relates to a smear-correcting device that corrects a smear of an image signal obtained from a CCD imaging device having a plurality of photoelectric conversion elements including a smear-correcting photoelectric conversion element.
2. Description of Related Art
It is a practice in the related art to correct a smear of an image signal obtained from a CCD imaging device as in the following manner. Namely, the image signal of a plurality of lines, obtained from smear-correcting photoelectric conversion elements of the imaging device, is averaged over on a column-by-column basis, to determine an average value per line. The average value per line is subtracted from an image signal of one line obtained from the other photoelectric conversion elements than the smear-correcting photoelectric conversion elements of the imaging device. (See, for example, JP-A-2000-50165 and JP-A-7-67038.)
However, in the smear correction, the average value is subtracted even from an image signal in which a smear component is not contained. In high-sensitivity photography, this deteriorates the S/N ratio in the signal, in which no smear components are contained, among the image signals obtained from the smear-correcting photoelectric conversion elements, and when noise components is contained in the image signal obtained from the smear-correcting photoelectric conversion elements, a vertical line takes place where no smears are occurring in an image corrected for smear.
For eliminating such a vertical line, it is effective to remove noise components by making a coring-subtraction of such an average value. However, of the image signals obtained from the smear-correcting photoelectric conversion elements, the signal containing a smear component is less deteriorated in its S/N ratio. In case coring-subtraction is made on those under the same condition as that of the signal not containing smear components, the signals containing smear components have a reduced average value which is insufficient in correcting, for smear, the region where smear is occurring.